Fluid heater casing



y 29, 1941- w. M. FIRSHING 2,251,014

' FLUID HEATER CASING Filed April 2,1938 5 Sheets-Sheet 1 William MFz'rs/n'rzy y 1941- w. M. FIRSHING 2,251,014

FLUID HEAEER CASI NG Filed April 2, 1938 5 Sheets-Sheet 2 Fig.2

ll ////////////////l////////////////////// ///////////////////1 ATTORNEY.

y 1941- w. M. FIRSHING 2,251,014

' mum HEATER CASING Filed April 2;' 1938 s Sheets-Sheet s I v INVENTOR.

[WE/ham M Hrs/2mg ATTORNEY.

29, 1941; I w. M. FIRSHING 2,251,014

FLUID HEATER CASING Filed April 2, 1938 S Sheets-She et T r r ,5

1N VENT OR.

ATTORNEY.

W. M. FIRSHING,

FLUID HEATER CASING July 29,1941.

Filed April 2, 1938 Fig J0 INVENTOR. VVi/liam MERE/U779 WRNEY.

I Patents I at 29, 1941 2,251,014 rwm nsa'rsa CASING William M. Firshing, Staten mend. N. 1., assignor 'to The Babcock & Wilcox Company, Newark,

N. J a corporation of New Jersey 7 Application April 2, 1938, Serial NIL-199,622

'15 Claims.

" 1- The present invention relates to the construction of fluid heater casings, and more particularly of fluid heater casings of the double walled .type having a gaseous fluid at a relatively high pressure circulating therethrough. My invention is particularly designed for and especially useful in steam boiler-units in which the air for combustion purposes is circulated under a relatively high pressure between the casing walls.

The main object of my invention is the provision of a fluid heater-casing of the character described which is particularly characterized by its gas tightness, strength, light weight, simplicity of construction, durability under high temperatures and corrosive conditions, and ease of assembly and disassembly.

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a partof this specification. For a better understanding of the invention, its operating advanillustrated and described a preferred embodiment of my invention.

01 the drawinssz' Fig. l is a sectional elevation of a marine steam boiler as installed witha casing constructed in.

' with the fuel burners omitted;

.' 4 is'an elevation of an outer casing panel:

Fig. is a section taken on the line I -is of Fig. 14.

l tage's and-specific objects attained by its use, ref- I erence should be. had to the accompanying drawings and descriptive matter in which I have The steam boiler illustrated in Figs. 1 and 2 is of the three-drum water tube type comprising an upper steam and water drum l0 and a pair of spaced lower water drums] I and I! connected thereto by a pair of oppositely inclined banks of water tubes l3 and I4 respectively. Thetubes in the bank I: are divided into two spaced groups and the space between'tlie-tube groups occupied by a group of transversely extending superheater tubes IS. The space between the tube banks serves as'the furnace chamber for the unit, and

is divided by a row of vertically extending studded tubes I 6 covered by refractory .to provide a partition dividing the furnacechamber into two sections. The tubes l6 extend between the drum I0 and a lower header I! which receives water from thedrum it through supply tubes l8.; Inclined banks of extended surface economizer tubes is and- 20 are arranged above the tube banks 13 and 7 II respectively. The described pressure parts are supported by drum pedestal supports and structural supports carried by the ship framework.

In accordance with my invention the pressure parts described are enclosed by a casing formed by substantially air-tight inner and outer panel walls 25 and 26 respectively, as shown-in Fig. 1, which are spaced apart to form a space therebetween for the passage of air to the fuel burners Figs. 5 and 6 are enlarged sections taken on thelines Hand 6-6 respectively of Fig. 4;

7 is an enlarged section illustrating the connection between a pair of outer casing panels; zFig. 8 is an elevation, partly in section, showof the unit. 7 The outer casing wall 26, as shown in Figs. 3

to I, is formed by a series of sheet metal panels 7 tions of the unit. As shown, each panel 21 is formed by a metal sheet ofrectangular shape ing thetie' bar connection between the casing Fig. 9 isa plan view'of the tie bar construction shown in Fig. 8:

- Fig. 10 is an elevation of one of the inner casing 1 a panel witn the liner plate and insulating blocks removed:

Fig. 11 is a section taken on the line lll| of Fig. 10; M

Fig. 12 is a section illustrating Fig. 13 is a transverse seclzlon illustrating the insulated door the connection be'tweenapairofinnercasingwnllpanels:

having cut-out corners and narrow'out-turned edge flanges 29 united at' the panel-corners by atomic hydrogen welding to form a shallow box-- likestructure open at its outer side. The panel.

sheets are made quite thin to reduce their weight.- Sheet'thicknesses of about .031" have been found satisfactory. Each panel is reinforced by a series of transversely spaced parallel stiflening members 30, preferably in the form of channel'membets having one flange portion spot welded to the 'installationof flange bolts. The edge flanges of the panels have a metal strip 23} spot welded spaces so formed caulked with asbestos rope 38 before the nut is tightened up. A strip of asbestos millboard 52 is inserted in the narrow space between the liner plate flanges 41 and the corresponding edge flanges 42 to minimize heat transmission to the liner plate. The air passing between the casing walls also aids in maintaining the liner plate cool. The portions of the edge flanges 42 projecting beyond the liner plate have metal strips 53 spot welded thereto. The inner wall panels are detachably connected to one another with gas-tight joints, as shown in Fig. 12,

or other suitable sealing material to form a gastight structure.

As shown in Fig. 3, the doors 28 are tightly clamped in position by removable peripheral clamps 35. Circular openings 36 are provided in the front section of the outer casing wall in which the fuel burners are mounted. Additional small openings 31 are arranged throughout the casing for the installation of soot-blower elements. The openings 31 register with corresponding openings in the inner casing wall 25. A rectangular air inlet opening 39 is formed in each side of the casing adjacent the rear end through which the combustion air supply for the unit is introduced under a positive pressure. The air so introduced flows between the casing irmer and outer walls to burner ports formed in the front section of the inner casing wall.

As shown in Figs. 8 to 13 the innercasing wall comprises a series of heat insulated panels 40 and doors 4| registering with corresponding parts of the outer casing wall. Each inner wall insulated panel 40 is also formed by a thin rectangular metal sheet having cut-out comer portions and out-turned flanged edge portions 42 "welded at the panel corners to provide a boxlike receptacle open at one side. The flanges 42 are of substantially greater width than the flanges on the outer wall panels, correspondingly increasing the depth of the panels 40. The panels 40 are reinforced by narrow stiffening channels 43 spot welded to the outer side of the panel sheet. Adjacent channels 43 have opposite ends secured to the corresponding edge flanges 42 by knee braces 48, as indicated in Fig. 10. Transversely extending channels 50 are arranged in the end compartments of the panel with their lower flanges spot welded to the inner sheet of the panel and secured at one end to the adjacent edge flange by knee braces 5|.

The channels 43 are transversely spaced sufflciently to permit the insertion of rows of blocks 44 of heat insulating material therebetween and between the end channels and side flanges with.- out requiring special cutting of the blocks. As shown in Figs. 11 and 12, the blocks 44 project beyond the top of the channels 43 but below the outer end of the edge flanges. The channel troughs and superjacent space between the block rows are preferably packed with loose insulation 45 of material similar to that used for the blocks. Uncalcined diatomaceous earth is preferred for both the blocks 44 and filling 45.

The outer side of the blocks 44 and filling 45 is covered by a thin metallic liner sheet 46 formed with in-turned edge flan es 41, which flt loosely within the edge flanges 42 and around the blocks 44. Block bolts 49 extend through the sheets 40 and 46 and blocks 44 to hold the blocks and panel sheets assembled. Gaskets are used under heads of'bolts 49 to prevent air leakage through the.

in the same manner as the outer wall panels shown in Fig. 7.

v The construction of the inner wall doors 4i, as shown in Fig. 13, follows the inner wall panel construction shown in Figs. 10-12, except that the inner sheets 60 have short edge flanges 6i and the liner sheets 62 are not flanged at their edges which extend beyond the flanges 6|. The endsof the doors are closed by'sheets 63 snugly fitting the flanges 6| and having their outer edges flanged at 64 to provide a detachable connection therefor to the liner sheet 62 through an interwound tightly around the threads of the bolt vening packing strip 65. Metal strips 66 are welded to the edges of the sheet 62 to reinforce the same. Fig. 13 illustrates a pair of doors withtheir adjoining sides clamped to a structural channel 10. The channel is heat insulated on its inner side by a U-shaped metallic sheet H welded to the edges of the channel flanges and the chamber so formed filled with heat insulating material 12. Studs 13 project from the channel web and carry clamps l4 and nuts 15 for holding the beaded edge of the packing strip 65 compressed between the channel web and the edgeportion of the liner sheet.

The outer casing wall is held in a predetermined spaced position relative to the inner wall by the tie bar construction shown in Figs. 8 and 9. Some of the inner wall panel bolts 33 carry elongated bars to each of which an L-shaped bar 8| is welded. Each bar 8| has one leg in contact with the sheet of an outer panel 21. A metal washer 82 is welded on the outer side of sheet 21 for the machine screw 83, which goes through the washer and sheet and is tapped into the tie bar, thus holding the parts in position.

As shown in Figs. 1 and 2, the portion of the furnace below the lower water drum is closed by vertical side walls 85 and a bottom pan 86, each of which is formed by an inner layer of dense fire brick 81, and outer layers of diatomaceous earth bricks 88. The bottom pan extends horizontally from the front or burner wall of the unit for nearly half the furnace length and slopes upwardly to the rear wall for its remaining portion. The lower outer walls and bottom of the air casing is formed by extending the outer panel wall structure at each side downwardly between the ship transversals into contact with the hull which serves as the outer bottom of the casing. The air space is also closed at its upper end by plates 89 at the upper end of the economizer sections.

All the parts of'the boiler casing in contact with the combustion gases are made of a corrosion resistant material of high tensile strength, preferably a chrome-nickel steel alloy in the 18-8 range. Any bolts and nuts in contact with the combustion gases are also made of corrosion resistant alloy or of dip calorized carbon steel.

In use as a marine boiler unit casing, the described construction has been successfully tested with casing pressures up to 23 in. of water column, i. e., lbs. per sq. ft. without substantial air leakage or casing distortion. The reinforced panel construction employed insures safe handling of the panel sections during manufacture and erection and substantially increases the strength of the casing structure to withstand the forces imposed by the relatively high designed air pressures. Thedescribed construction of the heat insulated members of the casing minimizes the temperature 01' the metal parts outside of it and also heat loss and consequently increases the overall efllciency of the unit. The described connection of the panel joints has been found particularly eflective in reducing air leakage to a negligibly small amount even with the relatively high air pressures contemplated.

While in accordance with the provisions of the statutes I have illustrated and described herein the best form of the invention now known to me,

those skilled in the art will understand that' changes may be made in the form of the apparatus disclosed without departing from the spirit of the invention covered by my claims, and that certain features of my. invention may sometimes be used to advantage without-a corresponding use of other features.

Iclaim:

l. A fluid heater casing comprising an inner wall'- and an outer wall spaced therefrom, said outer wall comprising a-series of sheet metal pan els having out-turned edge flanges, means forming a gas-tight connection between the edge flanges of adjacent panels, saidinner wall comprising a series of hollow sheet metal panels having out-turned edge flanges, rows of heat insu- 4 lating blocks within said inner wall panels, means forming a gas-tight connection between the edge flanges of adjacent inner wall panels, and metallic tie bars rigidly connecting said inner wall edge flanges to said outer wall panels.

2. A fluid heater casing comprising an inner wall and an outer wall spaced therefrom, said outer wall comprising a series of sheet metal panels having out-turned edge. flanges, means formwith out-turned edge flanges, and means forming a gas-tight detachable connection between the flanged edgeportions of adjacent panels, said means including a metal sheathed packing strip having beveled end portions, and loose heat insulatlng material caulked into the space between the adjacent beveled ends of adjacent packing strips.

7. A fluid heater casing comprising a plurality of metallic panels, each having ametallic sheetwith out-turned edge flanges, transversely spaced stifiening channels having one flange welded to the outer side of said sheet, metallic relni'orcing strips welded to the inside of said edge flanges, and means forming a gas-tight detachable connection between the flanged edge portions of adjacent panels, said means including a metal sheathed packing strip having beveled end portions, and loose heat insulating material caulked into the space between the adjacent beveled ends of adjacent packing strips.

8. A fluid heater casing comprising a series of heat insulated sheet metal panels each having a box-like inner sheet having out-turned edge flanges, transversely spaced stiffening members welded to the outer side of said inner sheet, heat insulating material arranged between and above said stiffening members, a liner sheet coveringthe outer side of said: insulating material and having in-turned edge flanges fltting within the flanged edges of said inner sheet, and a strip of ing a gas-tight connection between the edge flanges of adjacent panels, said inner wall comprising a series of heat insulated panels, each of said inner wall panels having an inner metallic sheet with out-turned edge flanges, rows of heat insulating blocks within said inner wall puels', an outer metallic sheet having in-turned edge flanges fitting within the edge flanges of said inner sheet, heat insulating strips between the edge flanges of said inner and outer sheets, means froming a gas-tight connection between the edge flanges of adjacent inner wall panels, and tie bars rigidly connecting said inner sheet edge flanges to said outer wall panels.

.3. A fluid heater casing comprising a plurality of metallic panels, each having a metallic sheet with out-turned edge flanges, transversely spaced stifiening channels having one flange welded along its length to the outer side of said sheet and the other flange cut away to form beveled ends terminating short of the adjacent edge flanges.

4. A fluid heater casing comprising a plurality of metallic panels, each having a metallic sheet with out-turned edge flanges, transversely spaced stiffening channels having one flange welded along its length to the outer side of said sheet and the other flange cut away to form beveled ends terminating short of the adjacent edge flanges, and metallic reinforcing strips welded to the inside of said edge flanges.

5. A fluid heater casing comprising a plurality heat insulating material between each pairof corresponding flanges on said inner and liner sheets.

9. A fluid heater casing comprising a series of heat insulated sheet metal panels, each having a box-like inner sheet having out-turned edge flanges, transversely spaced stifiening channels having one flange welded to the outer side of said inner sheet, blocks of heat insulating material arranged between said channels, a liner sheet covering the outer side of said insulating blocks and having i'n-turned edge flanges fltting within the flanged edges of said inner sheet, tying bolts connecting said sheets and extending through said insulating blocks, and a strip of heat insulating material between each pair of corresponding flanges on said inner and liner sheets.

10. A fluid heater casing comprising a series of heat insulated sheet metal panels, each having a box-like inner sheet having out-turned edge flanges, transversely spaced stiffening channels having one flange welded to the outer side or said inner sheet, blocks of heat insulating material arranged between said channels, a liner sheet covering the outer side of said insulating blocks and having in-turnededge flanges fitting within the flanged edges of said inner sheet, loose heat insulating material in the spaces between the outer side of said channels and said liner sheet, and a strip of heat insulating material between each pair of corresponding flanges onsaid inner-and liner sheets.

11. A fluid heater casing comprising a series of heat insulated sheet metal panels, each having a box-like inner sheet having out-turned edge flanges, transversely spaced stiifening channels welded to the outer side of said inner sheet and terminating short of the edge flanges thereof, knee braces rigidly connecting the opposite ends of alternate channels to the corresponding adjacent edge flange, heat insulating material arranged between said channels, a liner sheet covering the outer side of said insulating blocks and having in-turned edge flanges fitting within the flanged edges of said irmer sheet, and a strip of heat insulating material between each pair of corresponding flanges on said inner and liner sheets.

12. A fluid heater casing comprising a series of heat insulated sheet metal panels, each having a box-like inner sheet having out-turned edge flanges, transversely spaced stiffening channels welded to the outer side of said inner sheet and terminating short of the edge flanges thereof, knee braces rigidly connecting the opposite ends of alternate channels to the corresponding adjacent edge flange, blocks of heat insulating material arranged between said channels, a liner sheet covering the outer side of said insulating blocks, loose heat insulating material in the spaces between the outer side of said channels and said liner sheet, and tying bolts connecting said sheets and extending through said insulating blocks.

13. A fluid heater'casing comprising a series of heat insulated sheet metal panels, each having a box-like inner sheet having out-turned flanges, transversely spaced stifiening channels welded to the outer side of said inner sheet and terminating short of the edge flanges thereof, knee braces rigidly connecting the opposite ends of alternate channels to the corresponding adjacent edge flange, blocks of heat insulating material arranged between said channels, a liner sheet covering the outer side of said insulating blocks and having in-turned edge flanges fitting within the flanged edges of said inner sheet, loose heat insulating material in the spaces between the outer side of said channels and saidliner sheet, tying bolts connecting said sheets and extending through said insulating blocks, a strip of heat insulating material between each pair of corre sponding flanges on said'inner and liner sheets, and means forming a gas-tight detachable connection between adjacent flanged portions of adjacent inner sheets.

14. In a fluid heater casing having one side normally exposed to relatively high temperatures, a rigid metallic structural support member for said casing having a web and a pair of flanges projecting from the high temperature side of said web, and means for thermally insulating the high temperature side of said support member comprising a relatively thin sheet of heat resistant alloy metal arranged to close the space between said web flanges and having opposite edge portions welded to the edge portionsof said web flanges, and heat insulating material in the space enclosed by said metallic sheet and support member.

15. In a fluid heater casing having one side normally exposed to relatively high temperatures, a rigid metallic structural support member for said casing having a web and a pair of flanges projecting from the high temperature side of said web, and means for thermally insulating the high temperature side of said support member comprising a relatively thin sheet of heat resistant alloy metal arranged to close the space between said web flanges and having opposite flanged edge portions projecting oppositely relative to said web flanges and with said flanged edge portions welded to the edge portions of said web flanges,

and heat insulating material in the space enclosed by said metallic sheet and support member.

WILLIAM M. FIRSHING. 

